/*
// <copyright>
// dotNetRDF is free and open source software licensed under the MIT License
// -------------------------------------------------------------------------
// 
// Copyright (c) 2009-2017 dotNetRDF Project (http://dotnetrdf.org/)
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is furnished
// to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
// </copyright>
*/

using System;
using VDS.RDF.Query.Expressions;
using VDS.RDF.Query.Expressions.Conditional;

namespace VDS.RDF.Query.Builder.Expressions
{
    /// <summary>
    /// Represents a logical expression
    /// </summary>
    public sealed class BooleanExpression : TypedLiteralExpression<bool>
    {
        /// <summary>
        /// Wraps the <paramref name="expression"/> as a boolean expression
        /// </summary>
        public BooleanExpression(ISparqlExpression expression)
            : base(expression)
        {
        }

#pragma warning disable 1591
        public static BooleanExpression operator &(BooleanExpression left, BooleanExpression right)
        {
            return EitherArgumentNull(left, right) ?? new BooleanExpression(new AndExpression(left.Expression, right.Expression));
        }

        public static BooleanExpression operator |(BooleanExpression left, BooleanExpression right)
        {
            return EitherArgumentNull(left, right) ?? new BooleanExpression(new OrExpression(left.Expression, right.Expression));
        }

        private static BooleanExpression EitherArgumentNull(BooleanExpression left, BooleanExpression right)
        {
            if (ReferenceEquals(left, null) && ReferenceEquals(right, null))
            {
                throw new ArgumentNullException("left", "Either operator argument must be not-null");
            }
            if (ReferenceEquals(left, null))
            {
                return right;
            }
            if (ReferenceEquals(right, null))
            {
                return left;
            }
            return null;
        }

        public static bool operator false(BooleanExpression left)
        {
            return false;
        }

        public static bool operator true(BooleanExpression left)
        {
            return false;
        }

        public static BooleanExpression operator !(BooleanExpression expression)
        {
            return new BooleanExpression(new NotExpression(expression.Expression));
        }
#pragma warning restore 1591
    }
}